This is a divisional application of U.S. application Ser. No. 09/998,774, filed Nov. 30, 2001 (now U.S. Pat. No. 6,754,982).
The present invention relates to footwear and, more particularly, to a footwear construction and the method for making the same.
In the footwear industry, there is an ongoing effort to produce footwear including a cushioning system that provides both energy return characteristics and a high level of comfort for wearers. The need to produce such a cushioning system is particularly pronounced in the design of work, walking and athletic footwear, where reduction of fatigue and increased cushioning are primary objectives. For example, to minimize the effects of standing for long periods on hard surfaces (e.g., concrete floors) and walking on such surfaces, it is desirable to provide footwear that cushions the wearer's foot from the hard surface and also returns energy to the wearer during walking or running.
Conventionally, energy return and cushioning have been competing interests. Efforts to improve cushioning typically reduce energy return. One shoe sole assembly used to improve cushioning, disclosed in U.S. Pat. No. 5,233,767 to Kramer, includes multiple, hollow, uniform, vertical columns, which compress and bulge to provide shock absorption and, therefore, cushioning. Although the use of the uniform, vertical columns increases cushioning, energy return is sacrificed because the uniform, vertical columns may not rapidly snap back from the bulged shape after compression. In another footwear construction, disclosed in U.S. Pat. No. 6,131,310 to Fang, a flanged insole is positioned over an outsole including solid, cylindrical separating posts, but the insole is gapped a distance above each post. This structure increases cushioning due to the compression of the separating posts, however, energy return is lost because the columnar cylindrical posts may not rapidly snap back into pre-compression shape. Moreover, after the insole separates from the separating posts when weight is removed from the shoe, the separating posts cannot generate return energy to the insole due to the physical separation.
Although the cushioning systems of the prior art provide cushioning, there remains a long felt and unmet need for a footwear construction that provides a desired level of cushioning as well as energy return.